Heat asymmetries in nanoscale conductors: The role of decoherence and inelasticity

We investigate the heat flow between different terminals in an interacting coherent conductor when inelastic scattering is present. We illustrate our theory with a two-terminal quantum dot setup. Two types of heat asymmetries are investigated: electric asymmetry $\Delta_E$, which describes deviations of the heat current in a given contact when voltages are exchanged, and contact asymmetry $\Delta_C$, which quantifies the difference between the power measured in two distinct electrodes. In the linear regime, both asymmetries agree and are proportional to the Seebeck coefficient, the latter following at low temperature a Mott-type formula with a dot transmission renormalized by inelasticity. Interestingly, in the nonlinear regime of transport we find $\Delta_E\neq\Delta_C$ and this asymmetry departure depends on the applied bias configuration. Our results may be important for the recent experiments by Lee et al. [Nature (London) 498, 209 (2013)], where these asymmetries were measured.Comment: 9 pages, 5 figures. Minor changes; published versio

Experimental validation of an optical and thermal model of a Linear Fresnel Collector

2nd European Conference on Polygeneration – 30th March 1st April, 2011– Tarragona, SpainThis paper describes the design and validation of a mathematical model for a solar Fresnel collector. The function of the model is to simulate the optical and thermal dynamics of a Fresnel system for heating water. The model is validated using real data gathered from a cooling plant with double effect absorption chiller located in the School of Engineering University of Seville, Spain (Experimental cooling plant is also described in the paper). Comparison of calculated and plant measured data shows that the error is lower than 3% in the optical model and within 7% in the thermal model. The model uses a new approach to include a solar tracking mirror mechanism in one axis. This tracking has been designed to maximise the reception of available solar radiation by the absorption pipe. The thermal model used is based around classical models for solar receivers and it is validated with real operating data gathered from a supervisor system. The Fresnel model has been designed with sufficient flexibility to consider different geometries and thermal parameters, and may be used to simulate the performance of a proposed Fresnel collector system at any location

New records for the benthic marine flora of Chafarinas Islands (Alboran Sea, western Mediterranean)

Nuevas citas para la fl ora bentónica marina de las Islas Chafarinas (Mar de Alborán, Mediterráneo occidental

The effects of travelling reasons on social media resources and tourist expectations

Esta investigación tiene como objetivo examinar la relación de las fuentes del contenido generado por el usuario (UGC) en las redes sociales, que proviene generalmente de fuentes de lazos fuertes y fuentes de lazos débiles, en la generación de expectativas turísticas sobre los recursos básicos y los recursos o factores de apoyo de los destinos. También se analiza el efecto moderador de las razones para viajar en la relación de las fuentes UGC y las expectativas turísticas. Para esta investigación, se recogieron 375 encuestas. Los resultados señalan que las razones o motivos del viaje son un factor importante a considerar en la generación de las expectativas turísticas, y en nuestro caso, el UGC que provenía de las fuentes de lazos débiles influyen de manera significativa en la generación de expectativas del turista cuando viaja por motivos de trabajo.This research aims to examine the relationship of user generated content (UGC) sources in social media which is provided by strong-tie sources and weak-tie sources on tourist expectations on core resources and factor supporting of the destinations, and also analyze the moderate effect of the reasons of travelling on the relationship of UGC sources and tourist expectations. 375 samples were collected. The results demonstrate that travelling reasons is an important factor to consider about the origin of tourist expectations. The UGC that was provided by weak-tie source has influence on tourist expectations when they travel with business reason

Making Machines Learn. Applications of Cultural Analytics to the Humanities

The digitization of several million books by Google in 2011 meant the popularization of a new kind of humanities research powered by the treatment of cultural objects as data. Culturomics, as it is called, was born, and other initiatives resonated with such a methodological approach, as is the case with the recently formed Digital Humanities or Cultural Analytics. Intrinsically, these new quantitative approaches to culture all borrow from techniques and methods developed under the wing of the exact sciences, such as computer science, machine learning or statistics. There are numerous examples of studies that take advantage of the possibilities that treating objects as data has to offer for the understanding of the human. This new data science that is now applied to the current trends in culture can also be replicated to study more traditional humanities. Led by proper intellectual inquiry, an adequate use of technology may bring answers to questions intractable by other means, or add evidence to long held assumptions based on a canon built from few examples. This dissertation argues in favor of such approach. Three different case studies are considered. First, in the more general sense of the big and smart data, we collected and analyzed more than 120,000 pictures of paintings from all periods of art history, to gain a clear insight on how the beauty of depicted faces, in the framework of neuroscience and evolutionary theory, has changed over time. A second study covers the nuances of modes of emotions employed by the Spanish Golden Age playwright Calderón de la Barca to empathize with his audience. By means of sentiment analysis, a technique strongly supported by machine learning, we shed some light into the different fictional characters, and how they interact and convey messages otherwise invisible to the public. The last case is a study of non-traditional authorship attribution techniques applied to the forefather of the modern novel, the Lazarillo de Tormes. In the end, we conclude that the successful application of cultural analytics and computer science techniques to traditional humanistic endeavours has been enriching and validating

A framework for the analytical and visual interpretation of complex spatiotemporal dynamics in soccer

Pla de Doctorat Industrial de la Generalitat de CatalunyaSports analytics is an emerging field focused on the application of advanced data analysis for assessing the performance of professional athletes and teams. In soccer, the integration of data analysis is in its initial steps, primarily due to the difficulty of making sense of soccer's complex spatiotemporal relationships and effectively translating findings to practitioners. Recently, the availability of spatiotemporal data has given rise to applying statistical approaches to address problems such as estimating passing and scoring probability, or the evaluation of players' mental pressure. However, most of these approaches focus on isolated aspects of the sport, while coaches tend to focus on the broader interplay of all 22 players on the pitch. To address the non-stop flow of questions that coaching staff deal with daily, we identify the need for a flexible analysis framework that allows us to answer these questions quickly, accurately, and in a visually-interpretable way while capturing the complex spatial and contextual factors that rule the game. We propose developing such a comprehensive framework through the concept of the expected possession value (EPV). First introduced in basketball, EPV constitutes an instantaneous estimate of the expected points to be scored at the end of a possession. However, aside from a shared high-level goal, our focus on soccer necessitates a drastically different approach to account for the sport's nuances, such as looser notions of possession, the ability of passes to happen at any location, and space-time dependent turnover evaluation. Following this, we propose modeling EPV in soccer by addressing the question, "can we estimate the expectation of a team scoring or conceding the next goal at any time in the game?" From here, we address a series of derived interrogations, such as how should the EPV expression be structured so coaches can more easily interpret it? Can we produce calibrated and interpretable estimates for each of its components? Can we develop representative and soccer-specific features with the aid of coaches? Is it possible to learn complex features from raw level spatiotemporal data? Finally, and most importantly, can we produce compelling practical applications? These questions are successfully addressed in this thesis, where we present a series of contributions for both the machine learning and soccer analytics fields related to the modeling and practical interpretation of complex spatiotemporal dynamics. We propose a decomposed modeling approach where a series of foundational soccer components can be estimated separately and then merged to provide a single EPV estimation, providing flexibility to this integrated model. From a practical standpoint, we leverage several function approximation approaches to exploit complex relationships in spatiotemporal tracking data. An essential contribution of this work is the proposal of SoccerMap, a flexible deep learning architecture capable of producing accurate and visually-interpretable probability surfaces in a broad range of problems. Based on a large set of spatial and contextual features developed, we model and provide accurate estimates for each of the components of the EPV components. The flexibility and interpretation capabilities of the proposed model allow us to produce a broad set of practical applications related to on-ball performance, off-ball performance, and match analysis in soccer, and open the door for its future adaption to other sports. This thesis was developed under an Industrial Ph.D. program and carried out entirely at Fútbol Club Barcelona, which promoted a close collaboration with professional coaches. As a result, a vast part of the ideas developed in this thesis is now part of the club's daily player and team performance analysis pipeline.Sports analytics es una área de investigación de gran crecimiento y que se encuentra enfocada en la aplicación de análisis avanzado de datos para la evaluación del rendimiento de equipos y deportistas profesionales. En el fútbol, la integración del análisis de datos se encuentra en una etapa incipiente, principalmente dado la dificultad de evaluar los complejos factores espacio-temporales del juego, y de traducir los hallazgos al lenguaje de los entrenadores. La reciente disponibilidad de datos espacio-temporales ha dado pie a la aplicación de métodos estadísticos para explorar problemas tales como la estimación de la probabilidad de pasar o rematar exitosamente, o la evaluación de la presión mental durante el juego, entre muchos otros. Sin embargo, la mayoría de los estudios hasta la fecha se han enfocado en aspectos aislados del juego, mientras que el análisis de los entrenadores suele tomar una óptica más integral en la que considera la interacción de los 22 jugadores en el campo. En base a todo esto, identificamos la necesidad de contar con un completo sistema (framework) de análisis que permite responder al contínuo flujo de preguntas de los cuerpos técnicos de forma ágil y visualmente interpretable, y que al mismo tiempo permita capturar los complejos fenómenos espaciales y contextuales que rigen al fútbol. Proponemos el desarrollo de este sistema a través del concepto del valor esperado de la posesión (EPV, por sus siglas en inglés). El EPV, que fue introducido inicialmente en el baloncesto, constituye la estimación segundo a segundo de los puntos que se esperan obtener al final de una posesión de balón. Sin embargo, su adaptación al fútbol requiere de un enfoque completamente diferente para poder captar conceptos esenciales tales como que los pases pueden ir a cualquier ubicación en el campo, una definición menos rígida de la posesión de balón, y los efectos de perder el balón de acuerdo al espacio y tiempo en que este ocurre. En base esto, proponemos modelar el EPV enfocándonos en responder la siguiente pregunta ¿podemos estimar la esperanza de que un equipo marque o reciba el próximo gol, en cualquier instante del partido? A partir de aquí, desarrollamos una serie de preguntas derivadas relacionadas con la capacidad de proveer flexibilidad e interpretabilidad a nuestro modelo, así como desarrollar aplicaciones prácticas de forma ágil. Estas interrogantes son desarrolladas con éxito en esta tesis, donde presentamos una serie de contribuciones tanto al área de machine learning como a la de sports analytics. Proponemos un novedoso enfoque en el que se descompone el EPV en una serie de componentes esenciales, que pueden ser estimados de forma separada y luego integrados para producir una estimación única del EPV, dotando de mayor flexibilidad a este modelo integrado. Desde un punto de vista práctico, nos apoyamos en una serie de métodos de aproximación de funciones para sacar provecho de relaciones complejas en datos espacio-temporales de tracking. Derivado de esto, proponemos SoccerMap, una flexible arquitectura de deep learning capaz de producir superficies de probabilidad precisas y visualmente interpretables. Adicionalmente, nos apoyamos en una larga serie de variables espaciales y contextuales, desarrolladas en este trabajo, para modelar y proveer estimaciones acuradas de cada uno de los componentes del EPV. La flexibilidad de este modelo nos permite producir una vasta cantidad de aplicaciones prácticas relacionadas al rendimiento con y sin balón, y al análisis de partidos en fútbol, y marca un camino para su integración en otros deportes. Esta tesis fue desarrollada con el apoyo del Plan de Doctorados Industriales del Departamento de Investigación y Universidades de la Generalitat de Catalunya, y llevado a cabo en el Fútbol Club Barcelona, contando con la colaboración de entrenadores y profesionales del club.Postprint (published version

A metaheuristic approach for the repositioning problem in bike sharing systems (bss): a study case in Toluca, México

The impact of Bike Sharing Systems (BSS) in the world had experienced such success that nowadays most iconic cities in the world have adopted its own system. The particular characteristics of the user’s mobility in every city have not allowed developing a generalized procedure to operate the systems. Moreover, the lack of symmetry in the mobility patterns, and the dynamic users’ behavior lead to eventually “unbalance” the system, this is, to a lack of bikes at stations, and therefore bikes have to be repositioned to stations where effective demand is present, and there is no unified or scientifically supported methodology. In this paper we deal with a study case in Toluca city (Huizi system), in which the entity in charge of current operational activities wants to design a procedure scientifically based to perform repositioning daily activities at the minimum operational cost guarantying the availability of bikes for the users (service level). Due to operational requirements, this bi-objective problem was formulated using a dynamic scope and stated as a combinatorial optimization model and finally solved using a multi-objective evolutionary algorithm

Design, control and evaluation of a low-cost active orthosis for the gait of spinal cord injured subjects

Robotic gait training after spinal cord injury is of high priority to maximize independence and improve the living conditions of the patients. Current rehabilitation robots are expensive and heavy, and are generally found only in the clinical environment. To overcome these issues, we present the design of a low-cost, low-weight and personalized robotic orthosis for incomplete spinal cord injured subjects. The paper also presents a preliminary experimental evaluation of the assistive device on one subject with spinal cord injury that can control hip flexion to a certain extent, but lacks control of knee and ankle muscles. Results show that gait velocity, stride length and cadence of walking increased (24,11%, 7,41% and 15,56%, respectively) when wearing active orthoses compared to the case when the subject used the usual passive orthoses.Postprint (published version

Analytical approach to ground heat losses for high temperature thermal storage systems

A new approach to estimate the heat loss from thermal energy storage tank foundations is presented. Results are presented through analytical correlations based on numerical solutions for the steady-state heat conduction problem for thermal energy slab-on-grade tanks with uniform insulation. Model results were verified with other well-established benchmark problems with similar boundary conditions and validated with experimental data with excellent agreement. In addition to the TES foundation heat loss, new correlations for the maximum temperature and for the radial evolution of the temperature underneath the insulation layer are also provided, giving important information related to the tank foundation design. The correlated variables are of primordial importance in the tank foundation design because, due to the typical high operating storage temperatures, an inappropriate tank foundation insulation would lead not only to a not desired loss of energy but also to an inadmissible increase of the temperatures underneath the insulation layer, affecting the structural stability of the tank. The proposed correlations provide a quick method for the estimation of total tank foundation heat losses and soil maximum temperature reached underneath the insulation layer, saving time, and cost on the engineering tank foundation design process. Finally, a comprehensive parametric analysis of the variables of interest is made and a set of cases covering a wide range of tank sizes, insulation levels, depths to water table, and storage temperatures are solved

Majorana mode stacking, robustness and size effect in cylindrical nanowires

arXiv:1403.1755v1We discuss the robustness of Majorana edge modes in a finite quantum nanowire of cylindrical shape. The nanowire is modeled as a bidimensional cylindrical shell of semiconductor material with proximity-induced superconductivity and an intrinsic Rashba spin-orbit interaction. The latter is characterized by effective electric and magnetic fields in transverse direction of the nanowire. An applied external magnetic field pointing in an arbitrary orientation is also assumed. The numerical diagonalization of the Hamiltonian allows us to study the spectrum of the nanowire for different experimental configurations. The Majorana modes prove robust against tilting of the magnetic field away from the cylinder longitudinal axis, if the tilt direction is perpendicular to the effective spin-orbit magnetic field, but fragile otherwise. On the other hand, we find an increasing number of Majorana modes in the same cylinder edge for increasing values of the nanowire radius. We refer to this phenomenon as >stacking effect> and it occurs due to the orthogonality between Majorana mode wave functions. In this manner, different Majoranas take complementary positions on the nanowire surface. © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.Work supported by MINECO Grant No. FIS2011-23526, the Conselleria d’Educació, Cultura i Universitats (CAIB) and FEDER.N